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Date:   Thu, 27 Jan 2022 09:47:17 +0000
From:   Paul Cercueil <paul@crapouillou.net>
Subject: Re: [bug report] hwmon: Add "label" attribute
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     linux-hwmon@vger.kernel.org
Message-Id: <TI4D6R.WEHYEPI3R49G3@crapouillou.net>
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Hi,

Le jeu., janv. 27 2022 at 11:52:45 +0300, Dan Carpenter 
<dan.carpenter@oracle.com> a écrit :
> Hello Paul Cercueil,
> 
> This is a semi-automatic email about new static checker warnings.
> 
> The patch 073c3ea6c530: "hwmon: Add "label" attribute" from Jan 10,
> 2022, leads to the following Smatch complaint:
> 
>     drivers/hwmon/hwmon.c:825 __hwmon_device_register()
>     warn: variable dereferenced before check 'dev' (see line 810)
> 
> drivers/hwmon/hwmon.c
>    809
>    810		if (device_property_present(dev, "label")) {
>                                             ^^^
> The patch adds a new unchecked dereference

I will send a patch to address that.

I'm surprised that this function can be called with dev == NULL in the 
first place, though.

Cheers,
-Paul

>    811			err = device_property_read_string(dev, "label", &label);
>    812			if (err < 0)
>    813				goto free_hwmon;
>    814
>    815			hwdev->label = kstrdup(label, GFP_KERNEL);
>    816			if (hwdev->label == NULL) {
>    817				err = -ENOMEM;
>    818				goto free_hwmon;
>    819			}
>    820		}
>    821
>    822		hwdev->name = name;
>    823		hdev->class = &hwmon_class;
>    824		hdev->parent = dev;
>    825		hdev->of_node = dev ? dev->of_node : NULL;
>                                 ^^^
> Existing code checked for NULL
> 
>    826		hwdev->chip = chip;
>    827		dev_set_drvdata(hdev, drvdata);
> 
> regards,
> dan carpenter